Explanation:
The atmosphere of
a cometcomes and
goes.
Approaching the sun,
it swells as material from the
icy cometary nucleus
is warmed and evaporated by increasing sunlight.
Immense but tenuous and fleeting, the inner atmosphere or
inner "coma" of comet Hyakutake is seen in
this false color picture.
Oriented with the sunward direction toward the upper right,
the picture is a composite of
Hubble Space Telescope images
recorded on April 3 and 4, 1996.
It is about 14,000 km across (comparable to Earth's diameter)
and is a combination of images
showing dust reflected light (red) and ultraviolet light scattered from
Hydrogen atoms (blue).
Hyakutake's
Hydrogen atoms were produced by the breakup of water (H20)
molecules evaporating from its nucleus.
The Hydrogen data, combined with other observations,
indicate that this comet's nucleus, itself only a few km across,
was producing about 7 to 8 tons of water per second.